Reconstructing Holocene landscape development in Mongolia influenced by climate and pastoralism, based on geomorphological archives

该项目的关键问题，即人类从何时开始以及在多大程度上影响了蒙古半湿润到干旱的森林草原和草原地区的植被格局，尚未最终解决。坟墓和圣坛建筑提供的考古记录从青铜时代（距今3.5 ka BP）才开始。那时，游牧的生活方式，包括所有的群居动物，已经完全建立起来。然而，从猎人和采集者的生活方式过渡到畜牧业的前一段时期记录很少，因为这一时期的人工制品很少。这个项目是基于这样的假设：自新石器时代结束以来，畜牧业的发展导致了植被的实质性变化，这反过来又引发了地貌过程的加剧。在这个项目中，我们将开发和应用一种创新的科学方法，使我们能够在地方和区域尺度上确定人类引起的景观变化的时空格局。该方法将包括地貌-土壤学野外和实验室分析、数值测年、木炭和生物标志物分析的结合。所涉及的地貌学-土壤学方法基于以下因果链：人类活动，如伐木、放火和森林放牧，导致森林面积减少和草原植被退化。这些对景观的人为影响导致土壤侵蚀加剧，河流和风积沉积物重新分布。这一因果链导致了这一景观中分层沉积物的广泛分布，包括有机层、古土壤和木炭。这些沉积物为重建该地区全新世地貌动力学及其年代学过程提供了极好的资料。他们将是本项目的重点研究对象。通过对脂质生物标志物的分析，将获得家畜和相应的畜牧经济最早出现的直接证据。特别是，作为稳定化合物保存在古土壤和沉积物中的粪便类固醇，将作为当地存在相关动物物种的指标，如马、牦牛、牛、绵羊和山羊。地貌学、土壤学和地球化学方法的成功结合也将为古气候重建中人类活动信号的识别提供重要的新途径。这一贡献将具有高度相关性，因为蒙古晚全新世古气候发展重建中存在的不确定性主要来自代用数据中气候和人为信号的干扰，而这些干扰是现有方法难以分离的。

The key question of this project, i.e., since when and to what extent humans have influenced the vegetation pattern in the semihumid to arid forest steppe and steppe regions of Mongolia, has not yet been finally resolved. The archeological record provided by graves and sacral buildings only starts with the Bronze Age (3.5 ka BP). At that time, the nomadic lifestyle, including the whole spectrum of herd animals, was already fully established. However, the preceding period of the transition from the lifestyle of hunters and gatherers to stockbreeding is poorly documented, as artefacts of this period are rare. This project is based on the hypothesis that the development of pastoralism since the end of the Neolithic period led to a substantial change in the vegetation, which in turn triggered an intensification of geomorphological processes. In this project, we will develop and apply an innovative scientific approach that will allow us to identify the spatial and temporal patterns of the onset of human-induced landscape changes at local and regional scale. The approach will include a combination of geomorphological-pedological field and laboratory analysis, numeric dating, charcoal and biomarker analyses. The involved geomorphological-pedological methods are based on the following causal chain: Human activities such as woodcutting, fire-setting and wood pasture caused reduction of forest area and degradation of steppe vegetation by overgrazing. These anthropogenic impacts on the landscape resulted in increased soil erosion, as well as fluvial and eolian sediment redistribution. This causal chain led to a strikingly extensive distribution of stratified sediments in this landscape, containing organic layers, paleosols and charcoal. These sediments represent excellent archives for the reconstruction of the Holocene geomorphodynamics and their chronological course in this landscape. They will be the key study objects of this project. Direct evidence for the first occurrence of domestic livestock and corresponding pastoral economy will be obtained from the analysis of lipid biomarkers. In particular, fecal steroids that are preserved as stable compounds in paleosols and sediments, will serve as indicators of the local presence of relevant animal species such as horse, yak, cattle, sheep and goat.The successful implementation of the intended combination of geomorphological, pedological and geochemical methods will also contribute an important new approach to the identification of anthropogenic signals in paleoclimate reconstructions. This contribution will be highly relevant, as the existing uncertainties in the reconstruction of the late Holocene paleoclimatic development of Mongolia derive mainly from the interference of climatic and anthropogenic signals in the proxy data that are hardly separable by existing methods.